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Name: Eric
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A

Good day, I have often looked at the neither full nor new moon as dusk approaches and the sky turns to a darker blue. Sometimes, I have noticed that the dark part of the moon is darker than the sky itself - defining a circle of black and white against the dark blue background. I have come across a phenomenon called "earthshine" but that seems to be the process I describe in reverse: rather than the dark portions appearing blacker than the sky, earthshine as I understand it makes them appear lighter than the dark background. I must stress that this is not the phenomenon I am talking about. My question is: how can the moon seem to be darker than sky?

Dear Eric,

The Moon is never darker "than the sky." Earth shine means light reflected from the Earth lighting up the dark side of the Moon. If you look at this side with a telescope you will see it glowing dimly. If you were on the Moon there, you would see the Earth shining brightly.


David H. Levy

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